Cable networks need to transmit increasingly more data and programs and in order to achieve this the bandwidth of the networks needs to be stretched to accommodate transmission on higher frequencies. Higher frequencies produce higher losses, both in passive components like signal splitters and directional couplers, and also in coaxial cable conveying the signals.
Cable networks are required to be bi-directional with data transmitted from the network provider to the customer and data transmitted from the customer to the provider. This is achieved by using two specific frequency bands, one for upstream (data from customers) and one for downstream (data to customers). An example of these upstream and downstream bands are 5-65 MHz for upstream and 85 to 862 MHz for downstream. With the demand for more data, these upstream and downstream frequency bands will also stretch, e.g., 5-204 MHz for upstream and 258-1220 MHz or even 258-2000 MHz for downstream.
A typical cable installation at the customer premises comprises of a multiport amplifier with the input connected to the cable network and the outputs connected to different lengths of coaxial cable to feed different points in the house with cable TV signals. Different lengths of coaxial cable have different signal losses with the longest cable having the highest signal loss. The higher the frequency the higher the signal loss in the coaxial cable.